For information about TWAIN Direct please look here: http://twaindirect.org
Work on TWAIN Direct is ongoing, but I don’t expect any updates on its progress until September.

And for help with browser-based scanning, I recommend looking into the following vendors:
Dynamsoft (http://www.dynamsoft.com/Products/WebTWAIN_Overview.aspx)
Atalasoft (http://www.atalasoft.com/products/wingscan)

There is also a TWAIN C# project that may be helpful, depending on what coding you’re looking to do.
(https://sourceforge.net/projects/twainforcsharp/)